A new variant: BA.2.86

We have a new COVID-19 variant—BA.2.86—turning heads even among the calm, cool, and collected scientists.

This is what we know, what we don’t know, and what’s likely next.

What is happening?

SARS-CoV-2 continues to mutate.

This is expected, as this is what viruses do to survive. There was ~20% possibility of another “Omicron-like event” in 2023. Since Omicron arrived on the scene in November 2021, we’ve only seen incremental changes, which have created a ladder-like pattern (see panel A below). This is a good thing—we wanted Omicron to mutate because then we can predict where it’s going (for vaccines and our immunity, for example).

However, BA.2.86 doesn’t follow the ladder-like pattern. It has so many changes at once that it seems to come out of nowhere (see Panel B above). The virus likely mutated over time in one immunocompromised individual and then jumped to others.

Why is there concern?

As of now, we’ve only seen 7 cases in 4 countries. Usually, this isn’t enough to warrant concern, but some details are noteworthy:

• Mutations. The new variant has 35 mutations on the spike protein relative to what is currently circulating. (We pay attention to the spike protein because it’s the key to our cells.) This is an insane amount of change at once; it’s as big of an evolutionary jump as Wuhan → Omicron.

  

  (Raj Rajnarayanan)

• Community-level transmission. 6 cases are without travel history (and 1 U.S. case was a traveler from Japan). There is vast geographical distribution of the cases identified (Israel, the U.S., Denmark, and the U.K.). And we are seeing BA.2.86 in country-level wastewater samples (without corresponding reported cases). All of these point to undetected community transmission—it’s spreading.

  

  (Marc Johnson)

• Rapid spread. The 7 sequences are very similar, which means this variant hasn’t had time to change. In other words, it’s spreading quickly. 

What do we not know?

A lot.

Genetic surveillance is down 90%. Only 9,757 COVID-19 sequences were uploaded to the public database last week, compared to 137,878 for Omicron’s first week. In other words, we are searching in the dark.

On an immunologic level, it will take weeks to understand what these new mutations mean or, more importantly, what the combination of mutations means. Some labs, like those in Denmark, are already at work. In the meantime, we have a few educated guesses:

• Immune escape. One U.S. lab found that BA.2.86 has 16 known mutations that significantly escape our front-line immunity—antibodies. In other words, this will likely infect many people, regardless of prior immunity.

• Severity. We don’t know if this is more severe than Omicron or Delta, but it’s probably about the same severity level. This is because SARS-CoV-2 has historically evolved to escape antibodies (first line of defense) rather than T-cells (second line of defense) that primarily protect us from severe disease.

• Transmissibility. There’s a ceiling to contagiousness. It’s hard to imagine BA.2.86 spreading much better than Omicron, but nothing is ruled out yet.

Epidemiologically, we don’t know whether this will cause a wave yet; it may be a dud. But with more cases, it becomes more likely. Again, we are flying blind. We don’t have testing or case data like we did 2 years ago.

There is good news.

• This is still COVID-19. We aren’t returning to March 2020; our immune systems will still recognize the highly mutated variant, albeit suboptimally. This will protect a lot of us from severe disease.

• We can detect BA.2.86 on a PCR. Usually a swab has to go to a special lab for genome sequencing to know which variant caused the infection. However, BA.2.86 has a unique signal on the PCR directly—when positive, it lights up two channels instead of three. This is fantastic news because it means we can track this virus much easier and more quickly worldwide. CDC is doing this right now.

• Scientists are on top of it. While much of the public has moved on, public health is still working just as hard. WHO and CDC announced last week that they are monitoring this variant. U.K. came out with a fantastic risk assessment on Friday.

What’s next?

We are at the mercy of time to see what this variant does. Like a hurricane, we don’t know if it will fizzle away, become a category 5 disaster, or somewhere in between.

Regardless, our next moves include:

• WHO will determine if this is a new variant of concern—the highest risk classification. If so, it will be assigned a Greek name; next in line is “Pi.”

• Scientists are actively trying to understand how our immune systems react to BA.2.86 and if this impacts “real world” patterns. Their results should be coming in a few weeks.

• Companies will confirm (or deny) whether our tools (like the vaccines, Paxlovid, and antigen tests) work against BA.2.86.

Bottom line

We have a new variant on the horizon. We are in a lull now, waiting for the virus’s next move and for science to answer some key questions. Things should become more clear in the next two weeks.

Love, YLE

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“Your Local Epidemiologist (YLE)” is written by Dr. Katelyn Jetelina, MPH Ph.D.—an epidemiologist, wife, and mom of two little girls. During the day, she is a senior scientific consultant to several organizations. At night she writes this newsletter. Her main goal is to “translate” the ever-evolving public health world so that people will be well-equipped to make evidence-based decisions. This newsletter is free, thanks to the generous support of fellow YLE community members. To support this effort, subscribe below: